A thyristor in an n-type well is described in German Patent Application No. DE 20 26 778. The thyristor has a central p-type doping, in which an n-type doping zone is embedded. In addition, outer p-regions are provided in the n-type well. The outer p-regions, the n-type well, the inner p-type doping, and the inner n-type doping produce a thyristor. To isolate this thyristor dielectrically from other devices, the n-type well is completely surrounded by a p-region.